CDNJS vs Userstack
Same instrument, two spec sheets — measured, not claimed.
CDNJS vs Userstack: common questions
Which is more reliable, CDNJS or Userstack?
On our scheduled checks, CDNJS leads on measured uptime — CDNJS at 100% versus Userstack at 99.02% over 90 days. These are our own probe results, not provider claims; the uptime bars above show the day-by-day record for both.
Which is faster, CDNJS or Userstack?
CDNJS has the lower median latency in our checks — CDNJS responds in 281 ms versus Userstack at 443 ms (P50). Tail latency (P95) is in the table above; for most workloads the median is the number that shapes how the API feels.
Do CDNJS and Userstack need an API key?
CDNJS needs no key, while Userstack requires a free API key. If you want to start calling without signup, reach for CDNJS first.
Can I call CDNJS and Userstack from the browser?
Yes — both CDNJS and Userstack send CORS headers over HTTPS, so front-end code can fetch either directly with no backend proxy. That makes them easy to swap in a client-side app while you compare responses.
Are CDNJS and Userstack free for commercial use?
CDNJS has unclear commercial terms, and Userstack has unclear commercial terms. We track service terms and the data license as separate fields — see the Commercial use and Data license rows above, and confirm both before shipping either in a paid product.